package com.yanger.common.filter;

import java.util.regex.Pattern;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;

public class XSSRequestWrapper extends HttpServletRequestWrapper {
	public XSSRequestWrapper(HttpServletRequest servletRequest) {
		super(servletRequest);
	}

	@Override
	public String[] getParameterValues(String parameter) {
		String[] values = super.getParameterValues(parameter);
		if (values == null) {
			return null;
		}
		int count = values.length;
		String[] encodedValues = new String[count];
		for (int i = 0; i < count; i++) {
			encodedValues[i] = stripXSS(values[i]);
		}
		return encodedValues;
	}

	@Override
	public String getParameter(String parameter) {
		String value = super.getParameter(parameter);
		return stripXSS(value);
	}

	@Override
	public String getHeader(String name) {
		String value = super.getHeader(name);
		return stripXSS(value);
	}

	private String stripXSS(String value) {
		if (value != null) {
			// NOTE: It's highly recommended to use the ESAPI library and
			// uncomment the following line to
			// avoid encoded attacks.
			// value = ESAPI.encoder().canonicalize(value);
			// Avoid null characters
			value = value.replaceAll("", "");
			// Avoid anything between script tags
			Pattern scriptPattern = Pattern.compile("<script>(.*?)</script>", Pattern.CASE_INSENSITIVE);
			value = scriptPattern.matcher(value).replaceAll("");
			// Avoid anything in a
			// src="http://www.yihaomen.com/article/java/..." type of
			// e­xpression
			scriptPattern = Pattern.compile("src[\r\n]*=[\r\n]*\\\'(.*?)\\\'", Pattern.CASE_INSENSITIVE | Pattern.MULTILINE | Pattern.DOTALL);
			value = scriptPattern.matcher(value).replaceAll("");
			scriptPattern = Pattern.compile("src[\r\n]*=[\r\n]*\\\"(.*?)\\\"", Pattern.CASE_INSENSITIVE | Pattern.MULTILINE | Pattern.DOTALL);
			value = scriptPattern.matcher(value).replaceAll("");
			// Remove any lonesome </script> tag
			scriptPattern = Pattern.compile("</script>", Pattern.CASE_INSENSITIVE);
			value = scriptPattern.matcher(value).replaceAll("");
			// Remove any lonesome <script ...> tag
			scriptPattern = Pattern.compile("<script(.*?)>", Pattern.CASE_INSENSITIVE | Pattern.MULTILINE | Pattern.DOTALL);
			value = scriptPattern.matcher(value).replaceAll("");
			// Avoid eval(...) e­xpressions
			scriptPattern = Pattern.compile("eval\\((.*?)\\)", Pattern.CASE_INSENSITIVE | Pattern.MULTILINE | Pattern.DOTALL);
			value = scriptPattern.matcher(value).replaceAll("");
			// Avoid e­xpression(...) e­xpressions
			scriptPattern = Pattern.compile("e­xpression\\((.*?)\\)", Pattern.CASE_INSENSITIVE | Pattern.MULTILINE | Pattern.DOTALL);
			value = scriptPattern.matcher(value).replaceAll("");
			// Avoid javascript:... e­xpressions
			scriptPattern = Pattern.compile("javascript:", Pattern.CASE_INSENSITIVE);
			value = scriptPattern.matcher(value).replaceAll("");
			// Avoid vbscript:... e­xpressions
			scriptPattern = Pattern.compile("vbscript:", Pattern.CASE_INSENSITIVE);
			value = scriptPattern.matcher(value).replaceAll("");
			// Avoid onload= e­xpressions
			scriptPattern = Pattern.compile("onload(.*?)=", Pattern.CASE_INSENSITIVE | Pattern.MULTILINE | Pattern.DOTALL);
			value = scriptPattern.matcher(value).replaceAll("");
			scriptPattern = Pattern.compile("onerror(.*?)=", Pattern.CASE_INSENSITIVE | Pattern.MULTILINE | Pattern.DOTALL);
			value = scriptPattern.matcher(value).replaceAll("");
		}
		return value;
	}
}
